The subject matter of the invention relates to the general technical field of intervertebral connection devices for correcting weakening of the vertebrae or poor posture of the spinal column by providing stabilization about a longitudinal axis and on the antero-posterior plane.
More precisely, the subject matter of the invention relates to lumbar-lumbar or lumbar-sacral vertebrae connection devices for fixing to the anterior faces of said vertebrae.
Numerous types of intervertebral connection device are known in the state of the art. Thus, in particular from French design application No. 96/7390, an anterior osteosynthesis plate for lumbar vertebrae is known comprising an elongate body adapted to cover at least part of the anterior portions of two consecutive vertebrae. The elongate body possesses an anterior face and a posterior face opposite thereto for pressing against the anterior faces of the vertebrae. The elongate body has end zones interconnected by a connection zone, and each end zone is hook-shaped. Each end zone is provided with a through hole for a screw that is to be anchored in a vertebral body.
Such a plate makes it possible to interconnect two vertebrae after reestablishing the intervertebral space. Such a plate prevents the vertebrae from turning about the longitudinal axis and tilting in the antero-posterior plane, and it enables the vertebrae to be stabilized by encouraging arthrodesis thereof.
The above-described anterior lumbar plate presents a certain number of drawbacks. Thus, it appears that each hook-shaped end portion of the plate is for anchoring to the anterior edges of the plates of the vertebral bodies. Unfortunately, it must be understood that from one patient to another, firstly the anterior edges of the plates are of varying profiles, and secondly the size of the intervertebral space varies. As a result, it is difficult to position such a plate correctly, even when plates are available in a set of plates having different dimensions and profiles. In addition to the need to have a wide variety of plates, it should also be observed that poor positioning of such a plate degrades the quality of intervertebral connection, and consequently degrades intervertebral stability during bone fusion.
The object of the invention is to remedy the above-specified drawbacks by proposing an anterior osteosynthesis plate for lumbar-lumbar or lumbar-sacral vertebrae, that is designed to present great adaptability during installation, independently of the dimensions presented by the intervertebral space and of the dimensions and/or profile of the vertebral bodies to which such a plate is to be fixed.
To achieve this object, the invention provides an anterior osteosynthesis plate for lumbar-lumbar or lumbar-sacral vertebrae, the plate being of the type comprising:
an elongate body:
adapted to cover at least part of the anterior portions of two consecutive vertebrae;
possessing an anterior face and an opposite posterior face designed to be pressed against the anterior faces of the vertebrae;
presenting end zones that are interconnected by a connection zone; and
provided with two through holes for anchoring screws, each formed in a respective one of the end zones.
According to the invention, the posterior face of the body of the plate presents a bearing surface in each end zone, which bearing surface is designed to come into contact with the anterior face of the corresponding vertebra, the bearing surfaces being firstly inclined to define an obtuse angle between them in the sagittal plane matching the relative angle between the anterior portions of the two vertebrae, and secondly being interconnected in the connection zone by a concave extension such that at least the posterior face of the body presents a profile that is concave in the sagittal plane.
According to another characteristic of the invention, the through holes of the plate are constituted by bores formed in such a manner that their axes define respective angles of inclination in the sagittal plane relative to the planes in which the associated bearing surfaces extend, so that said axes diverge from each other going away from the body.
This characteristic makes it possible to obtain screw anchoring in diverging directions suitable for taking up the forces that might act on the plate.
Various other characteristics appear from the following description given with reference to the accompanying drawings which show embodiments and implementations of the invention as non-limiting examples.